The present invention relates to a recording device for recording data on a magneto-optical recording medium.
A magneto-optical recording and reproducing system can be regarded as a Gaussian low pass filter if the entire part is considered to be a base band transmission line. Therefore, an increase in the recording density causes inter-symbol interference between the minimum signals of adjacent recording regions and thus deteriorates a regenerated signal waveform.
As one of the methods of preventing such inter-symbol interference, the method of correcting the frequency characteristic of the entire transmission line to a Nyquist characteristic by providing an equalizer at a later stage of a magneto-optical recording and reproducing system is known. However, since the transmission band is limited in this method, it is difficult to apply the method to recording and reproducing of a high density magneto-optical disk.
Therefore, the PR (Partial Response) method in which inter-symbol interference is not eliminated but a signal is transmitted with inter-symbol interference is employed for recording and reproducing of a high density magneto-optical disk.
A transmission system in which the PR method is applied to a magneto-optical disk will be described with reference to FIG. 9. Referring to FIG. 9, a precoder 701, a magneto-optical disk 704 in which a signal is recorded and regenerated by an optical pickup 702 and a magnetic head 703, and an equalizer 705 form the transmission system. Precoder 701 eliminates error propagation caused when a code that is transmitted by the PR method is decoded. Equalizer 705 performs waveform equalization of an RF signal regenerated from magneto-optical disk 704. That results in inter-symbol interference having known correlation as the transmission system.
Multi-value discrimination portion 706 estimates the most possible state of a signal by maximum likelihood decoding. More specifically, the amplitude correlation of the PR method is utilized to refer to the state of a decoded signal before time for identification (or before and after identification time) and to estimate the most analytically possible value to be the signal state at the identification time.
In signal transmission of the PR method, it is desirable in some cases to divide a precoded signal (signal after being precoded) into blocks of a prescribed bit number and to insert an intrinsic pattern or the like of the drive system before and after each block. For example, magneto-optical disk 704 may be caused to have a clock component in advance and data may be recorded on locations other than that of the clock component.
If data is inserted after precoding, however, the code correlation of a precoded signal cannot be maintained at a location where division into blocks is found. Then, a decoding error occurs in maximum likelihood decoding which utilizes signal correlation before and after identification time.
An object of the present invention is to provide a recording device capable of inserting data in a precoded signal without causing a decoding error of data.
According to one aspect of the present invention, a recording device for recording data on a recording medium of a method in which data is reproduced by utilizing inter-symbol interference includes precode means for precoding input data to adjust to the recording medium, format means for dividing the precoded data into a plurality of data blocks and adding a corresponding intrinsic pattern to an end of each of the plurality of data blocks, pattern determination means for determining the corresponding intrinsic pattern for each of the plurality of data blocks and outputting the corresponding intrinsic pattern to the format means, and record means for recording an output of the format means on the recording medium, wherein the pattern determination means determines the corresponding intrinsic pattern to reduce a decoding error of data at each end of the plurality of data blocks. Preferably, the pattern determination means selects one of predetermined at least two intrinsic patterns as the corresponding intrinsic pattern for each of the plurality of data blocks. Preferably, the corresponding intrinsic pattern is formed of such data among data included in a data block adjacent to a corresponding data block that is adjacent to an end of the corresponding data block before division into blocks.
Therefore, according to the above described recording device, even when an intrinsic pattern is inserted and recorded for precoded data and the recorded data is read out and subjected to waveform equalization to perform maximum likelihood decoding, code correlation at a location where division into blocks is performed can be maintained. It is therefore possible to prevent occurrence of the decoding error of maximum likelihood decoding at the block division location.
According to another aspect of the present invention, a recording device for recording data on a recording medium of a method in which data is reproduced by utilizing inter-symbol interference includes precode means for precoding input data to adjust to the recording medium, format means for dividing the precoded data into a plurality of data blocks and adding a corresponding first intrinsic pattern to a front end of each of the plurality of data blocks and a corresponding second intrinsic pattern to a rear end of each of the plurality of data blocks, pattern determination means for determining the corresponding first intrinsic pattern and the corresponding second intrinsic pattern for each of the plurality of data blocks, and record means for recording an output of the format means on the recording medium, wherein the pattern determination means determines the corresponding first intrinsic pattern according to the rearmost data of a data block located immediately before a corresponding data block, and determines the corresponding second intrinsic pattern according to the rearmost data of the corresponding data block. Preferably, the corresponding second intrinsic pattern is combined with the rearmost data of the corresponding data block to generate traceback. Preferably, the rearmost data of the corresponding first intrinsic pattern is identical to the rearmost data of the data block located immediately before the corresponding data block.
Therefore, according to the above described recording device, even when an intrinsic pattern is inserted and recorded for precoded data and the recorded data is read out and subjected to waveform equalization to perform maximum likelihood decoding, code correlation at a location where division into blocks is performed can be maintained. It is therefore possible to prevent occurrence of the decoding error of maximum likelihood decoding at the block division location. When an intrinsic pattern which generates traceback is inserted, maximum likelihood decoding can be completed for each data block.
The foregoing and other objects, features and advantages of the present invention will become apparent from the following details of the present invention understood in conjunction with the attached drawings.